I discovered yesterday Preemt RT have changed so that it handles priorities for interrupts properly. Or at least as good as possible because there may be SMI, System Management Interrupts in bios. My reasonable modern quad core computer have a maximum delay of around 50µs, it is not as good as a micro controller but good enough for a reliable 1ms thread.
> We in fact do use hardware to make things better - just as the lowest level > possible. Build a micro controller that reads encoders and outputs PWM > and that is a good fit for linuxcnc and they are very good at that. I have micro controller that read encoders and output PWM and it is in sort of built for this task. To send encoder output to linuxcnc for position control loop is a detour and I will modify later to send position directly. The micro controller I have chosen is available from around $1 in high quantity although maybe only one motor for this price otherwise it is two. > Of course I mostly look from a big machine control side - if you are wanting > to operate something else I can see wanting to use a tablet or phone and > in this case the GUI being separate would be very helpful. > But that still doesn't mean putting the motion controller inside a > microcontroller. It would be good to separate GUI. The motion must be put on something running real time reasonable well but demand is not very high. > In all I don't see the motivation for putting the motion controller anywhere > but were it is - unless coding motion controllers in micro controllers is > something > you just like to do. (which certainly is not a bad thing) If motion controller is put on micro controller there will be nothing else except communication protocols and this is an advantage compared to a Linux operating which is rather complex. I have written software many times where I used nested interrupts with priority for scheduling and this is a very simple easy to understand system if there are only a few tasks. It does not work for large systems but it keep software simpler for small systems. Nicklas Karlsson ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=272487151&iu=/4140 _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
